German Patent Application DE 40 30 333 A1 describes a locking device for laterally joined contactors whose actuating members for the movable contacts are electromagnetically moved in a direction substantially perpendicular to the connecting sidewalls. The two contactors are received in a common lower housing part. The actuating members, of the two contactors have facing projections, which stand back from the connecting sidewalls and between which is supported a locking pin that is movable in a direction perpendicular to the connecting sidewalls, which are provided with openings at this location. When switching on one of the two contactors, the projection thereof moves the locking pin toward the other contactor. When attempting to switch on the other contactor, the projection thereof strikes the locking pin. The holding force of the electromagnetic operating mechanism of the already switched-on contactor is greater than the pickup force of the electromagnetic operating mechanism of the other contactor, which prevents the actuating member of the other contactor from moving to the ON position. It is a disadvantage of this locking device that, on the one hand, the actuating members are required to move in a direction perpendicular to the connecting sidewalls, and that the locking effect is no longer guaranteed when the electromagnetic operating mechanisms are operated with a holding power that is markedly reduced compared to the pickup power, which is what is generally being aimed at.
German Patent DE 195 48 480 C1 describes a locking device of this type which avoids the aforementioned disadvantages. The moving direction of the actuating members is perpendicular to the front face of the laterally joined contactors. A support element is inserted in opposite first slots in the connecting sidewalls, the support element supporting a locking element in the form of an anchor which is able to pivot in a direction perpendicular to the connecting sidewalls. The connecting sidewalls have opposite second slots for receiving the anchor. When energizing the electromagnetic operating mechanisms of both contactors simultaneously, the anchor engages recesses of both actuating members and prevents both contactors from being switched on. The recesses are each bounded by a front inner surface, a central inner surface, and a rear inner surface, which extend parallel or perpendicular or at an angle to the front faces, respectively. When energizing the electromagnetic operating mechanism of one contactor alone, the anchor is moved out of the recess of the actuating member of this contactor and pushed into the recess of the actuating member of the other contactor, thereby effectively locking the same from being switched on. The two contactors are connected by connecting elements whose outer legs engage like brackets around ribs extending from the connecting sidewalls and whose central leg engages in a positively locking manner in a recess formed in the connecting sidewalls. In this locking device, two complicated parts are needed for the support element and the anchor, which involves high tooling costs. The existing locking stroke of the locked contactor requires exact matching of the geometries of the first slots, the support elements, the anchors, the recesses, and of the geometry, support and kinematics of the actuating members.
U.S. Pat. No. 4,409,575 A shows a mechanical interlock mechanism for mechanically connected contactors, including a locking element in the form of a rolling element, such as a cylindrical roller or a hollow cylindrical roller, which is supported in a connecting frame between the spaced apart contactors and is actuated by the contact frame of the respective contactor that is energized. The disadvantage here is the need for a connecting frame and the associated, relatively large spatial distance between the opposite sidewalls of the two contactors.